Counter-rotating propeller systems (sometimes referred to as contra-rotating propeller systems) include two propellers that are rotated in opposite directions about a common axis. Counter-rotating propeller systems are used in many industries, such as in the aerospace industry (e.g., on fixed-wing aircraft, helicopters, etc.), for water travel (e.g., on torpedoes, boats, etc.), for pumping systems, on ducted fans, etc. Counter-rotating propeller systems are often desirable because they are more efficient than single-propeller systems. To drive the propellers in opposite directions, a counter-rotating propeller system utilizes a transmission having two coaxial output shafts. An outer output shaft is connected to the second (downstream) propeller, and an inner output shaft extends through the outer output shaft and is connected to the first (upstream) propeller in front of the second propeller. The transmission drives the output shafts in opposite directions, which rotates the propellers in opposite directions about the common axis.